#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int fib(int n)
    {
        return dfs(n);
    }
    int dfs(int n)
    {
        if (n == 0 || n == 1) return n;

        return dfs(n - 1) + dfs(n - 2);
    }
};